Lam F, Farner D S
Cell Tissue Res. 1976 Jun 11;169(1):93-109. doi: 10.1007/BF00219310.
In male White-crowned Sparrows subjected to 20 h daily photoperiods there is an approximately 3-fold increase in the plasma concentration of luteinizing hormone (LH) on the first long day after which a quasi-stable level is maintained for at least 42 days. This increase is followed by an increase in numbers of cells of Leydig and an enhancement of their steroidogenic features, a decrease in transitional interstitial cells, and an increase in plasma level of testosterone. With the decline in plasma LH, as photorefractoriness develops, the steroidogenic features of the cells of Leydig undergo disorganization. For as yet unexplainable reasons the plasma levels of testosterone decline before the decrease in plasma LH and before the degeneration of the steroidogenic features of the cells of Leydig.
在每天接受20小时光照周期的雄性白冠雀中，在第一个长日照后，促黄体生成素（LH）的血浆浓度大约增加了3倍，之后维持至少42天的准稳定水平。这种增加之后，睾丸间质细胞数量增加，其类固醇生成特征增强，过渡性间质细胞减少，睾酮血浆水平升高。随着光不应性的发展，血浆LH下降，睾丸间质细胞的类固醇生成特征发生紊乱。由于尚未明确的原因，睾酮的血浆水平在血浆LH下降之前以及睾丸间质细胞类固醇生成特征退化之前就开始下降。
